Support for offset cylinders of printing machines

ABSTRACT

Offset cylinders of printing cylinders are mounted rotatably on a shaft, provided at both ends with formed discs with equally shaped circumferences. The shaft is supported in the sidewalls of the machine by sets of adjustable rollers bearing against said formed discs. At one end of said shaft is fixed a sleeve and mounted pivotably a lever provided with means for adjustment of their relative position. Control cam means are provided, acting on said lever pivotably mounted on the shaft, adjusting the position of said formed discs with respect to their supporting rollers and thus also the position of the offset cylinder with respect to the form cylinder and pressure cylinder.

United States Patent [72] Inventor Josef Jurny Sebranice, Czechoslovakia[21] Appl. No. 847,083 [22] Filed Aug. 4, 1969 [45] Patented Nov. 9,1971 [73] Assignee Adamovske Strojirny, narodni podnik Adamov,Czechoslovakia [54] SUPPORT FOR OFFSET CYLINDERS 0F PRlNTlNG MACHINES 8Claims, 5 Drawing Figs.

[52] U.S.Cl 101/218 [51] Int. Cl 134117/04, 1341f 13/36 [50] FieldnISearch 101/137, 139, 140, 143, 144, 182, 184,218,248, 247, 217

[56] Relerences Cited UNITED STATES PATENTS 2,615,393 10/1952 Albrecht101/184 Primary Examiner-.1. Reed Fisher Arlorney-Richard Low ABSTRACT:Offset cylinders of printing cylinders are mounted rotatably on a shaft,provided at both ends with formed discs with equally shapedcircumferences. The shaft is supported in the sidewalls of the machineby sets of adjustable rollers bearing against said formed discs. At oneend of said shaft is fixed a sleeve and mounted pivotably a leverprovided with means for adjustment of their relative position, Controlcam means are provided, acting on said lever pivotably mounted on theshaft, adjusting the position of said formed discs with respect to theirsupporting rollers and thus also the position of the offset cylinderwith respect to the form cylinder and pressure cylinder.

PATENTEDNDV sum 3,618,51

saw 1 or a INVENTOR 7553f far/1 PATENTEI] NOV 9 IBYI SHEET 8 0F 4INVENTOR J55 a ar/1y BY SUPPORT FOR OFFSET CYLINDERS OF PRINTINGMACHINES BACKGROUND OF THE INVENTION This invention relates to themounting of the shaft of an offset cylinder of printing machines and toa method for its pressure engagement with other cylinders.

The offset cylinder of a printing machine, in addition to its mainfunction which is the transmission of a picture by means of the offsetrubber coating, has to be arranged so as to enable a subsequent mutualpressure engagement with the form cylinder and with the pressurecylinder in predetermined cycles.

Known offset printing machines have the shaft of the offset cylindermounted by means of its hearings in twin eccentric sleeves which bytheir relative turning cause the shaft and thus also the offset cylinderto approach to the pressure cylinder.

In lighter printing machines the offset cylinder is generally mountedrotatably on a shaft, both extremities of which are eccentric and areprovided with bearings, supported between three eccentric bolts, bymeans of which the pressure with respect to the form and pressurecylinder is adjusted together with the adjustment of the printingmachine. The turning of the eccentric shaft causes the movement of theoffset cylinder to engage first with the form cylinder and then byfurther turning also with the pressure cylinder. Other arrangementscomprise differently shaped discs maintained on each end of the shaftbetween three rollers and supporting rotatably the shaft of the offsetcylinder. By turning the shaped discs, the offset cylinder is moved intoengagement with the form cylinder and later also with the pressurecylinder. The adjustment of the pressure according to the thickness ofthe paper is accomplished by turning the eccentric bolts ofa coupleofsupporting rollers.

A drawback of the first mentioned arrangement is the sliding support ofthe shaft and of the eccentric sleeves which requires some device forlubricating the sliding surfaces. A further drawback is the mounting ofthe shaft of the offset cylinder by means of three elements so that evenin case of a maximum accuracy the rigidity of the offset cylinder isinfluenced by the necessity of providing three mounting clearances.

A drawback of the second arrangement is that the offset cylinder ismounted rotatably on a shaft, which is in turn mounted by its eccentricextremities in bearings, usually roller bearings, which are by means oftheir external rings mounted between two eccentric bolts, theeccentricity of which is required for the adjustment of pressure withrespect to printing cylinders. This double mounting of the off cylinderrequiring clearance in the bearings also unduly influences its rigidity.Another drawback shows up in the course of disengagement of the offsetcylinder from the form cylinder where by turning the eccentric shaft theaxial distance of the offset and printing cylinder and thus also thedistance of their toothed driving wheels is large. During operation ofthe machine when no printing is performed, the transmission gears arerather noisy. The increased axial distance influences also unfavorablythe shape of the evolute of the toothed driving wheels of the printingcylinders.

The arrangement with differently shaped discs has the drawback, thattheir control has to be solved independently in both sidewalls of themachine and also the adjustment of the pressure in dependence on thethickness of the printed paper has to be performed by means of anauxiliary tool individually on both sides of the printing machine. Themechanism for turning the shaped discs has to be very rigid and due tothe shape of the circumferential curves of said discs a considerableforce is required for their turning. Due to the rigidity of the offsetcylinder a substantial pressure on the pressure cylinder has to bemaintained.

SUMMARY OF THE INVENTION It is an object of this invention to provide asupport of the offset cylinder, which would enable an easy adjustment ofthe position of the offset cylinder.

It is a further object of this invention to enable an easy adjustment ofthe offset cylinder for printing of paper of different thickness.

It is still another object to significantly limit the influence of wearon all clearances.

Bearing these and other objects in mind the supporting structure of theoffset cylinder comprises a shaft on which the offset cylinder isrotatably mounted by roller bearings, with formed discs with equallyshaped circumference fixed on both ends of said shaft. The shaft issupported in the sidewalls of the printing machine by sets of threeadjustable rollers, bearing against said formed discs. On one end of theshaft is fixed a sleeve and a pivotal lever with means for adjustment oftheir relative position. A control cam acting by way of said lever onsaid sleeve adjusts the position of the formed disc with respect to itssupporting rollers and thus also the position of the offset cylinderwith respect to the form cylinder and the pressure cylinderrespectively. The circumference of the formed discs is shaped so as toapproach first the offset cylinder to the form cylinder and subsequentlyto the pressure cylinder.

The arrangement of the support of the offset cylinder ac cording to thisinvention has the advantage, that the maximum rigidity of mounting isachieved, whereby any clearance of mounting of the shaft of the offsetcylinder is eliminated by the use of a spring-loaded pressure roller.The formed discs fixed on the ends of the shaft of the offset cylinderenable the ap' proach and removal of the offset cylinder with respect tothe form cylinder and pressure cylinder to the required distance so thatthe axial distance of the driving gears is negligibly changed. Thecircumference of the formed discs causes the offset cylinder to approachin pressure engagement with the form cylinder and with the pressurecylinder according to a predetermined time table. Another advantage ofthis arrange ment is that the pressure between the offset and pressurecylinder can be easily adjusted according to the thickness of theprinted paper without affecting the pressure with respect to the fonncylinder by manual operation of a single adjusting screw with referenceto a scale. Another advantage arises from the circumstance that bothformed discs are fixed directly on the shaft of the offset cylinder. Theindividual control systems for the formed disc on both ends of the shaftare not required and the whole control is accomplished by merely turningthe shaft by means of a lever. The offset cylinder can be easilydisassembled by retracting the levers supporting the supporting rollers.As the formed disc has a shape which is complementary with respect tothe supporting rollers, the turning of the shaft with the formed discsis easy and the spring of the spring-loaded supporting roller eliminatesinaccuracies in manufacture, contrary to known arrangements where thisspring is completely engaged in relieving pressure of the formed discs.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the object of thisinvention is shown in the accompanying drawings where FIG. 1 is anelevation of the mounting of the offset cylinder with parts shown insection FIG. 2 is a side view in a section taken along the plan A-A asindicated in FIG. 1, with positions I and II of the offset cylinder FIG.3 is a similar view with position III and IIIA of the offset cylinderFIG. 4 is the same view with the turned-down pivoting lever and FIG. 5shows in enlarged scale the circumference of the formed disc as in FIG.2 in the individual positions.

DESCRIPTION OF PREFERRED EMBODIMENT The arrangement according to thisinvention consists of an offset cylinder I mounted by means of bearings2 rotatably on a shaft 3. Formed discs are fixed by means of set screws4 at both ends of the shaft 3, each of said formed discs 5 mountedbetween rings 6 and 34 respectively. which are themselves supported oneccentric bolts 7 and 33, fixed in the sidewalls 8 of the machine andbetween a roller 9 rotatably supported on the bolt 10, fixed on apivotable lever ll. The pivotable levers are located on both sides ofthe offset cylinder pivotably and are supported on bolts 12, fixed inthe sidewalls 8. Adjusting screws 35 are provided on each of thepivotable levers l1, and have springs 13, resting with their other endsagainst sleeves I4, fixed to the sidewalls 8, bearing against saidadjusting screws 35. Additional adjusting screws located in thesidewalls 8 bear against the faces of the shaft 3 of the offsetcylinder 1. A sleeve 16 is fixed on one end of the shaft 3 and a lever17 is pivotably mounted at this end. The sleeve 16 is provided with anadjusting screw I8 bearing against the lever 17. A scale 19 is providedon the face ofthe lever 17. A pointer 20 and a bolt 21 is fixed on thesleeve 16. A spring 22 is suspended with one end on the bolt 21 and withits other end on a bolt 23 fixed in the sidewall 8 of the printingmachine.

The lever 17 is supported by a roller 24'rotatably supported on a bolt25 fixed to a two-arm lever 26, itself pivotably supported on a bolt 27fixed to the sidewall 8. A roller 29 is rotatably supported on a bolt 28on the other end of the twoarm lever 26, said roller 29 being inengagement with the circumference ofa cam 32 of a not shown mechanism,causing a deviation of the cam 32 and thus also the bringing of theoffset cylinder 1 in pressure engagement with the form cylinder 30 andwith the pressure cylinder 30 and with the pressure cylinder 31respectively.

The shape of the formed discs 5 is more exactly shown in FIG. 5. Theroller 34 is substantially situated at the connecting line of thecenters of the offset cylinder 1 and of the pressure cylinder 31, theroller 6 at the connecting line of the ofi'set cylinder 1 and the formcylinder 30, and the roller 9 is situated substantially opposite to bothsaid rollers 6 and 34. The disc 5 is divided into a series ofcorresponding sectors I, II, III; I, II', III, and; I", II", III"associated respectively with each of the rollers 6, 34 and 9. The shaft3 with the discs 5 is during operation of the printing machine turnedfor an angle indicated for instance between positions] and III. Theshape of the circumference of the discs 5 between position I and II iscircular, passing between positions II and III into a spiral-shapeddepression. The shape of the parts between position I' and II is aconvex depression passing between positions 11' and III into a circularshape. The shape of the discs 5 between position I" and II" isdetermined by the shape of the circular part between position land IIand by the shape of the part between positions I and II' in order tomeet the condition, that all three rollers 6, 34 and 9 remain stable inthe course of turning the shaft 3. The shape of the part betweenpositions II" and III" is equally complementary to the shape of partsbetween positions II and III and the circular part between positions IIand III'.

The described structure operates as follows:

In the position I as indicated in FIG. 2 the offset cylinder 1 isremoved from the form cylinder 30 and from the pressure cylinder 31whereby no printing is performed. At the beginning of printing, it isnecessary to bring the offset cylinder 1 first in engagement for onerevolution with the form cylinder 30 in order to transmit ink to theprinting plate. By turning the cam 32, along which the roller 29 of thetwo arm lever 26 is rolling, the movement of lever 26 is transmitted byway of the roller 24 to the lever I7. By this means the lever 17 isturned, the turning of which caused the formed discs 5 and thus also theshaft 3 of the offset cylinder 1 to be displaced from position 1 toposition 11 with respect to the roller 34 and correspondingly withrespect to the other rollers 6 and 9. The

formed discs 5 allows the offset cylinder 1 to move towards the formcylinder 30 until engagement occurs as seen in FIG. 2 by the dottedoutline of cylinder shown by numeral II. As the circumference of theformed discs 5 corresponding to places between position I and II isexactly circular, the axial distance between the ofiset cylinder 1 andthe pressure cylinder 31 remains the same. The circumferential shape ofthe formed discs 5 has however, between positions I and II the shape ofa convex curve, which causes the offset cylinder 1 to approach towardsthe form cylinder 30. Further turning of the cam 32 by means of the notshown mechanism causes the formed discs 5 to be turned from position 11to position Ill and as the circumferential curve has between positionsII and III is a spiral shape. the offset cylinder 1 is moved towards thepressure cylinder 31 until engagement occurs, as seen in the dottedoutline of cylinder 1 shown by numerals III. The pressure between theoffset cylinder I and the form cylinder 30 does not change in course ofthis operations as the circumference of the formed discs 5 at placescorresponding to positions between II and III is exactly circular.Reversing the direction at which the lever 17 is turned will trip offthe offset cylinder and reverse the operation. Thus the sequentialengagement of the form cylinder 30 and the pressure cylinder 31 by theoffset cylinder 1 is obtained by oscillation of the discs 5 between thelimits set by movement of lever 17. The shape of cam 32 or its propermovement can control lever 17 to effect cyclical movement. Theadjustment according to the thickness of the paper is accomplished bymeans of the adjusting screw I8. By turning the adjusting screw 18pressure is generated on the lever 17 which turns the shaft 3 and theformed discs 5 from position III into position IIIA as indicated in FIG.3. The turning of the formed discs 5 between positions III and IIIAcauses due to the spiral shape of the circumferential curve a pressingor removal of the offset cylinder 1 with respect to the pressurecylinder 31 according to the thickness of the printed paper sheets. Theformed discs 5 fixed on both ends of the shaft 3 are pressed by rollers9 mounted on the pivotable levers l1 and is biased by springs 13 betweenthe two rings 6 and 34 supported on the eccentric bolts 7 and 33. Theformed discs 5 have their circumference extended at places of engagementof the rollers 9 to such an extent that a minimum of force is requiredfor turning of the formed discs 5. All clearances of the rings 6, 34 andof the rollers 9 are removed by the force of the springs 13, so that therigidity of the offset cylinder 1 is solely determined by the clearanceof the bearings 2.

Iclaim:

I. In an offset printing machine having a rotatable offset cylindermounted on a shaft and being shiftable into engagement with a formcylinder and a pressure cylinder respectively, a support for said offsetcylinder comprising a frame having a pair of spaced walls, a shaped discfixed to said shaft at each end of said cylinder, a plurality of rollersmounted in each of said sidewalls of said frame to bear against thecircumference of said disc and to support the same, a sleeve fixed to atleast one end of said shaft, a lever freely mounted about said shaft inproximity of said sleeve and extending radially outward therefrom, meansfor fastening said lever to said sleeve and means for angularlydisplacing said lever to rotate said shaft and change the relativeposition of said discs with respect to the supporting rollers, saiddiscs being formed with cooperating surfaces adapted to engage with saidrollers to cause said offset cylinder to selectively move into and outof engagement with said form and pressure cylinders respectively, ondisplacement of said lever.

2. The support according to claim 1 including means for mounting saidsupport rollers on said wall for adjustable radial movement with respectto the shaft of said offset cylinders.

3. The support according to claim 2 wherein said rollers are spacedabout the periphery of said shaft, at least one of said rollers beingprovided with biasing means for resiliently urging said rollers againstsaid shaped discs and thereby against said other rollers.

4. The support according to claim 3 wherein said biased roller ismounted on a pivotal crank supported by the wall of said frame andprovided with spring means for normally biasing said crank to cause saidroller to engage said disc.

5. The support according to claim 1 wherein said means for fasteningsaid lever to said sleeve is adjustable.

6. The support means according to claim 1 wherein said rollers comprisethree in number, the first roller determining together with the shapeddisc the position of the offset cylinder with respect to the formcylinder, the second roller determining together with said shaped discthe position of the offset cylinder with respect to the pressurecylinder, the third roller urging against said disc so as to maintaincontact of said rollers with said disc, said discs being formed withpredetermined sectors having circumferential contours corresponding toeach of said rollers, said sectors being arranged so that engagement ofsaid disc causes cooperation between said discs and rollers to effectsequential operation with said offset cylinder, said disc causing saidfirst roller to move said offset cylinder to engage said form cylinderand subsequently to cause said first and second rollers tosimultaneously move said offset cylinder to simultaneously engage saidform and pressure cylinders.

7. The support according to claim 6 wherein the disc sectorscorresponding to the first roller have a circumference comprising acircular portion and a depressed portion and wherein the sectors of thedisc corresponding to said second roller comprises a depressed portionand a circular portion, the circular portion corresponding with saidfirst roller and the depressed portion corresponding to said secondroller causing engagement of said offset cylinder with said formcylinder only and the depressed portion corresponding with said firstroller and the circular portion corresponding with said second rollercausing engagement of the offset cylinder with both said form andpressure cylinders simultaneously, and the sectors corresponding to saidthird roller having a circumference comprising an extending curvedportion adapted to maintain the disc and engagement under uniformpressure against said first and second rollers during rotation of saiddisc.

8. The support means according to claim 7, wherein said third roller ispivotally mounted and provided with resilient biasing means for urgingsaid roller against said disc.

1. In an offset printing machine having a rotatable offset cylindermounted on a shaft and being shiftable into engagement with a formcylinder and a pressure cylinder respectively, a support for said offsetcylinder comprising a frame having a pair of spaced walls, a shaped discfixed to said shaft at each end of said cylinder, a plurality of rollersmounted in each of said sidewalls of said frame to bear against thecircumference of said disc and to support the same, a sleeve fixed to atleast one end of said shaft, a lever freely mounted about said shaft inproximity of said sleeve and extending radially outward therefrom, meansfor fastening said lever to said sleeve and means for angularlydisplacing said lever to rotate said shaft and change the relativeposition of said discs with respect to the supporting rollers, saiddiscs being formed with cooperating surfaces adapted to engage with saidrollers to cause said offset cylinder to selectively move into and outof engagement with said form and pressure cylinders respectively, ondisplacement of said lever.
 2. The support according to claim 1including means for mounting said support rollers on said wall foradjustable radial movement with respect to the shaft of said offsetcylinders.
 3. The support according to claim 2 wherein said rollers arespaced about the periphery of said shaft, at least one of said rollersbeing provided with biasing means for resiliently urging said rollersagainst said shaped discs and thereby against said other rollers.
 4. Thesupport according to claim 3 wherein said biased roller is mounted on apivotal crank supported by the wall of said frame and provided withspring means for normally biasing said crank to cause said roller toengage said disc.
 5. The support according to claim 1 wherein said meansfor fastening said lever to said sleeve is adjustable.
 6. The supportmeans according to claim 1 wherein said rollers comprise three innumber, the first roller determining together with the shaped disc theposition of the offset cylinder with respect to the form cylinder, thesecond roller determining together with said shaped disc the position ofthe offset cylinder with respect to the pressure cylinder, the thirdroller urging against said disc so as to maintain contact of saidrollers with said disc, said discs being formed with predeterminedsectors having circumferential contours corresponding to each of saidrollers, said sectors being arranged so that engagement of said disccauses cooperation between said discs and rollers to effect sequentialoperation with said offset cylinder, said disc causing said first rollerto move said offset cylinder to engage said form cylinder andsubsequently to cause said first and second rollers to simultaneouslymove said offset cylinder to simultaneously engage said form andpressure cylinders.
 7. The support according to claim 6 wherein the discsectors corresponding to the first roller have a circumferencecomprising a circular portion and a depressed portion and wherein thesectors of the disc corresponding to said second roller comprises adepressed portion and a circular portion, the circular portioncorresponding with said first roller and the depressed portioncorresponding to said second roller causing engagement of said offsetcylinder with said form cylinder only and the depressed portioncorresponding with said first roller and the circular portioncorresponding with said second roller causing engagement of the offsetcylinder with both said form and pressure cylinders simultaneously, andthe sectors corresponding to said third roller having a circumferencecomprising an extending curved portion adapted to maintain the disc andengagement under uniform pressure against said first and second rollersduring rotation of said disc.
 8. The Support means according to claim 7,wherein said third roller is pivotally mounted and provided withresilient biasing means for urging said roller against said disc.